fixup! Arcyd: sanitize git abstraction
Revert "start copying files to make arcyd2"

This reverts commit 4b46f8cafa919c98699058abf19165d77c456aa5.

Conflicts:
	meta/package_deps/expected-package-deps
Check for unreferenced components in precommit.sh

Emit an error if any files under 'py' are not reachable from the
dependency graph of the binaries we distribute.

Test Plan:
$ ./precommit.sh
fails due to dead code, remove the dead code
$ ./precommit.sh